Effects of electron correlation and the Breit interaction on one- and two-electron one-photon transitions in double K hole states of He-like ions(10 ≤ Z ≤ 47)

The x-ray energies and transition rates associated with single and double electron radiative transitions from the double K hole state 2s2p to the 1s2s and 1s^2 configurations of 11 selected He-like ions(10 ≤ Z ≤ 47) are calculated using the fully relativistic multi-configuration Dirac–Fock method(MCDF). An appropriate electron correlation model is constructed with the aid of the active space method, which allows the electron correlation effects to be studied efficiently. The contributions of the electron correlation and the Breit interaction to the transition properties are analyzed in detail. It is found that the two-electron one-photon(TEOP) transition is correlation sensitive. The Breit interaction and electron correlation both contribute significantly to the radiative transition properties of the double K hole state of the He-like ions. Good agreement between the present calculation and previous work is achieved. The calculated data will be helpful to future investigations on double K hole decay processes of He-like ions.

Synergistic effect of Co（Ⅱ）-hole and Pt-electron cocatalysts for enhanced photocatalytic hydrogen evolution performance of P-doped g-C3N4

g-C3N4 is a metal-free semiconductor and a potential candidate for photocatalytic H2 production,however,the drawbacks,rapid recombination rate and limited migration efficiency of photogenerated carriers,restrict its photocatalytic activity.Herein,Co(II)as a hole cocatalyst modified P-doped g-C3N4 were successfully prepared to ameliorate the separation efficiency of photoinduced carriers and enhance the photocatalytic hydrogen production.The photocatalytic results demonstrated that the P-doped g-C3N4(PCN)exhibited higher photocatalytic activity compared with pure g-C3N4,while Co(II)/PCN photocatalyst exhibited further enhancement of photocatalytic performance.The proposed possible mechanism based on various characterizations is that P-doping can modulate the electronic structure of g-C3N4 to boost the separation of photogenerated-e-and h+;while the synergistic effect of both Co(II)(as hole cocatalyst)and Pt(as electron cocatalyst)can not only lead to the directional shunting of photogenerated e+-h?pairs,but further accelerate the photogenerated electrons transfer to Pt in order to join the photocatalytic reduction process for hydrogen evolution.As a result,the transportation and separation of photoinduced carriers were accelerated to greatest extent in the Pt/Co(II)/PCN photocatalyst.

Suppression of electron and hole overflow in GaN-based near-ultraviolet laser diodes

In order to suppress the electron leakage to p-type region of near-ultraviolet GaN/In_xGa_（1-x ）N/GaN multiple-quantumwell（MQW） laser diode（LD）, the Al composition of inserted p-type AlxGa_（1-x）N electron blocking layer（EBL） is optimized in an effective way, but which could only partially enhance the performance of LD. Here, due to the relatively shallow GaN/In_（0.04）Ga_（0.96）N/GaN quantum well, the hole leakage to n-type region is considered in the ultraviolet LD. To reduce the hole leakage, a 10-nm n-type Al_xGa_（1-x）N hole blocking layer（HBL） is inserted between n-type waveguide and the first quantum barrier, and the effect of Al composition of Al_xGa_（1-x）N HBL on LD performance is studied. Numerical simulations by the LASTIP reveal that when an appropriate Al composition of Al_xGa_（1-x）N HBL is chosen, both electron leakage and hole leakage can be reduced dramatically, leading to a lower threshold current and higher output power of LD.

Electrostatic Structure of the Electron Phase-space Holes Generated by the Electron Two-stream Instability with a Finite Width

Space satellite observations in an electron phase-space hole(electron hole) have shown that bipolar structures are discovered at the parallel cut of parallel electric field, while unipolar structures spring from the parallel cut of perpendicular electric field. Particle-in-cell(PIC) simulations have demonstrated that the electron bi-stream instability induces several electron holes during its nonlinear evolution. However, how the unipolar structure of the parallel cut of the perpendicular electric field formed in these electron holes is still an unsolved problem,especially in a strongly magnetized plasma(Ω_e >ω_(pe), where Ω_e is defined as electron gyrofrequency and ω_(pe) is defined as plasma frequency, respectively). In this paper, with two-dimensional(2D) electrostatic PIC simulations, the evolution of the electron two-stream instability with a finite width in strongly magnetized plasma is investigated. Initially, those conditions lead to monochromatic electrostatic waves, and these waves coalesce with each other during their nonlinear evolution. At last, a solitary electrostatic structure is formed. In such an electron hole, a bipolar structure is formed in the parallel cut. of parallel electric field, while a unipolar structure presents in the parallel cut of perpendicular electric field.

Different charging behaviors between electrons and holes in Si nanocrystals embedded in SiN_x matrix by the influence of near-interface oxide traps

Si-rich silicon nitride films are prepared by plasma-enhanced chemical vapor deposition method, followed by thermal annealing to form the Si nanocrystals（Si-NCs） embedded in Si Nx floating gate MOS structures. The capacitance–voltage（C–V）, current–voltage（I–V）, and admittance–voltage（G–V） measurements are used to investigate the charging characteristics. It is found that the maximum flat band voltage shift（△VFB） due to full charged holes（～ 6.2 V） is much larger than that due to full charged electrons（～ 1 V）. The charging displacement current peaks of electrons and holes can be also observed by the I–V measurements, respectively. From the G–V measurements we find that the hole injection is influenced by the oxide hole traps which are located near the Si O2/Si-substrate interface. Combining the results of C–V and G–V measurements, we find that the hole charging of the Si-NCs occurs via a two-step tunneling mechanism. The evolution of G–V peak originated from oxide traps exhibits the process of hole injection into these defects and transferring to the Si-NCs.

Effect of Ion Dynamics on the Evolution of Electron Phase-space Holes

The evolution of two-dimensional（2D） electron phase-space holes（electron holes） has been previously investigated with electrostatic Particle-in-Cell（PIC） simulations,which neglect ion dynamics.The electron holes are found to be unstable to the transverse instability,and their evolution is determined by the combined action between the transverse instability and the stabilization by the background magnetic field.In this paper,the effect of ion dynamics on the evolution of an electron hole is studied.In weakly magnetized plasma(Ωe<ωpe,whereΩe andωpe are electron gyrofrequency and plasma frequency,respectively),the electron hole is still unstable to the transverse instability. However,it evolves a little faster and is destroyed in a shorter time when ion dynamics is considered. In strongly magnetized plasma(Ωe>ωpe),the electron hole is broken due to the lower hybrid waves, and its evolution is much faster.

A Novel Micro-hole Electrode Used to Investigate Electron Transfer Reactions at ITIES

A novel micro-hole electrode was fabricated to investigate the electron transfer reaction at the interface between two immiscible electrolyte solutions (ITIES). The electron transfer reaction between ferro/ferricyanide in aqueous phase (W) and ferrocene in 1, 2-dichloroethane (O) phase was studied as a test experiment. The results showed that the diffusion coefficient obtained from the micro-hole electrode was consistent with that obtained at macro-interface. Due to its simplicity and the very small IR drop it will be a useful tool for the study of ITIES systems.

NeoMinkowskian Cosmological Black Hole, Poincaré’s Gravific Electron and Density of CBR

In the previous paper (JMP 2014) we showed that there exists a NeoMinkowskian Gravitational Expanding Solution of GR (General Relativity) with CC (Cosmological Constant). We prove now that NeoMinkowskian Vacuum (non-baryonic Fluid), with gravitational (first) density (dark energy) and gravitational waves (at light speed), corresponds to the Gravitation Field of a Cosmological Black Hole (CBH). The latter predicts furthermore a basic emission of Radiation (CBR) from Hubble spherical singular Horizon to the inside of CBH (unlike Hawking’s emission) at an initial singular time. Our solution is then compatible with a well-tempered Big Bang and Expanding Universe (Escher’s Figure, see Penrose, 3) but incompatible with inflation. The latter is based on Hypothesis of a so-called Planck’s particle (Lemaitre’s primitive atom) characterized by a so-called Planck length. We prove that we can short-circuit this unstable particle with a stable cosmological Poincaré’s electron with gravific pressure. It is well known that electron is a stranger in usual Minkowskian vacuum (dixit Einstein). The stranger electron can be perfectly integrated in NeoMinkowskian Radiation fluid and then also (with its mass, charge and wavelength) in (second density of) CBR. Everything happens as if the leptonic mass of the electron were induced by our cosmological field. The unexpected cosmological model proposed here is the only one that predicts numerical values of (second) density and temperature of CBR very close to the observed (COBE) values.

Cutting edge preparation of microdrills by shear thickening polishing for improved hole quality in electronic PCBs

Printed circuit boards(PCBs)are representative composite materials,and their high-quality drilling machining remains a persistent challenge in the industry.The finishing of the cutting edge of a microdrill is crucial to drill performance in machining fine-quality holes with a prolonged tool life.The miniature size involving submicron scale geometric dimensions,a complex flute shape,and low fracture toughness makes the cutting edge of microdrills susceptible to breakage and has been the primary limiting factor in edge preparation for microdrills.In this study,a newly developed cutting edge preparation method for microdrills was tested experimentally on electronic printed circuit boards.The proposed method,namely,shear thickening polishing,limited the cutting edge burrs and chipping on the cutting edge,and this in turn transformed the cutting edge’s radius from being sharp to smooth.Moreover,the edge–edge radius could be regulated by adjusting the processing time.PCB drilling experiments were conducted to investigate the influence of different cutting edge radii on wear,hole position accuracy,nail head value,and hole wall roughness.The proposed approach showed 20%enhancement in hole position accuracy,33%reduction in the nail head value,and 19%reduction in hole wall roughness compared with the original microdrill.However,a threshold is needed;without it,excessive shear thickening polishing will result in a blunt edge,which may accelerate the wear of the microdrill.Wear was identified as the primary factor that reduced hole quality.The study indicates that in printed circuit board machining,microdrills should effectively eliminate grinding defects and maintain the sharpness of the cutting edge as much as possible to obtain excellent drilling quality.Overall,shear thickening polishing is a promising method for cutting edge preparation of microdrills.Further research and optimization can lead to additional improvements in microdrill performance and contribute to the continued advancement of printed circuit board manufacturing.

Theoretical and numerical simulation investigation of deep hole dispersed charge cut blasting

Drilling and blasting methods have been used as a common driving technique for shallow-hole driving and blasting in rock roadways.With the advent of digital electronic detonators and the need for increased production efciency,the traditional blasting design is no longer suitable for deep hole blasting.In this paper,a disperse charge cut blasting method was proposed to address the issues of low excavation depth and high block rate in deep hole undercut blasting.First,a blasting model was used to illustrate the mechanism of the deep hole dispersive charge cut blasting process.Then,continuous charge and dispersed charge blasting models were developed using the smooth particle hydrodynamics-fnite element method(SPHFEM).The cutting parameters were determined theoretically,and the cutting efciency was introduced to evaluate the cutting efect.The blasting efects of the two charging models were analyzed utilizing the evolution law of rock damage,the number of rock particles thrown,and the cutting efciency.The results show that using a dispersed charge improves the cutting efciency by about 20%and the rock breakage for the deep hole cut blasting compared to the traditional continuous charge.In addition,important parameters such as cutting hole spacing,cutting hole depth and upper charge proportion also have a signifcant impact on the cutting efect.Finally,the deep hole dispersed charge cut blasting technology is combined with the digital electronic detonator through the feld engineering practice.It provides a reference for the subsequent deep hole cutting blasting and the use of electronic detonators in rock roadways.

Model of Preformed Hole-Pairs in c-Axis Transport in Cuprate Superconductors

Model of hole-pairs in electrical transport along ab plane in cuprate superconductors has already been proposed. It has been found to be in the shape of 3dx2–y2 orbital of an electron in an atom. This time, model of hole-pairs in transport along c-axis in cuprate superconductors is proposed. In ab-plane, hole-pairs are formed along CuO2 plane;one hole-pair covering 9 - 10 two dimensional CuO2 unit cells in 3dx2–y2 configuration. In the investigation of c-axis hole-pairs, cuprate superconductors have been sub-divided into three categories depending on the number of CuO2 planes/formula unit. There is a little different treatment for finding out the order parameter in each category. Coherence lengths along ab-planes are of the order of a few tens of Angstroms, whereas along c-axis, they are less than even their a-, b-lattice constants. In cuprates with 2 or 3 CuO2 planes, the order parameter is of 3dz2–x2 type in zx-plane with lobes along both the axes much constrained. For cuprates with a single CuO2 layer, the order parameter is of 3dx2–y2 type, but its dimensions are less than a-, b-lattice constants.

Model of Preformed Hole-Pairs in Cuprate Superconductors

A model of preformed hole-pairs in cuprate superconductors has been proposed based on some experimental results i.e., 1) electron paramagnetic resonance spectra of quenched superconductors which show very frequently the fragment (CuO)4 broken off from the CuO2 layer in the structure, 2) 41 meV peak observed in neutron diffraction and nuclear magnetic resonance spectra of superconductors, 3) Heisenberg exchange interaction leading to ferromagnetism observed in CuO which is an essential ingredient of all superconductors and some generally accepted conclusions i.e., a) that the order parameter in superconductors has dx2–y2 symmetr and b) coherence length is of the order of 15 - 20 Angstrom. Heisenberg exchange interaction between two (CuO4) plaquettes each containing a lattice hole binds the two holes which are the charge carriers in the cuprate superconductors. It is not very clear whether the hole-pair is in the triplet or singlet state, but the triplet state is supported by the experimental observation of ferromagnetism in the parent material CuO. The proposed hole-pair singlet is different from Zhang-Rice singlet.

Exciton dynamics in luminescent carbon nanodots： Electron-hole exchange interaction

The electron-hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots （Cdots） is still not clear. In this study, we have developed a simple and efficient one-step strategy to synthesize luminescent Cdots using the pyrolysis of oleylamine. The sp^2 clusters of a few aromatic rings are responsible for the observed blue photoluminescence. The size of these clusters can be tuned by controlling the reaction time, and the energy gap between the π-π＊ states of the sp^2 domains decreases as the sp^2 cluster size increases. More importantly, the strong electron-hole exchange interaction results in the splitting of the exciton states of the sp^2 clusters into the singlet-bright and triplet-dark states with an energy difference ΔE, which decreases with increasing sp^2 cluster size owing to the reduction of the confinement energy and the suppression of the electron-hole exchange interaction.

Nonlinear optics in the electron-hole continuum in 2D semiconductors:two-photon transition, second harmonic generation and valley current injection

We investigate two-photon transitions to the electron-hole scattering continuum in monolayer transition-metal dichalcogenides, and identify two contributions to this nonlinear optical process with opposite circularly polarized valley selection rules. In the non-interacting limit, the competition between the two contributions leads to a crossover of the selection rule with the increase of the two-photon energy. With the strong Coulomb interaction between the electron and hole, the two contributions excite electron-hole scattering states in orthogonal angular momentum channels, while the strength of the transition can be substantially enhanced by the interaction. Based on this picture of the two-photon transition, the second harmonic generation(SHG) in the electron-hole continuum is analyzed, where the Coulomb interaction is shown to greatly alter the relative strength of different cross-circular polarized SHG processes. Valley current injection by the quantum interference of one-photon and two-photon transition is also investigated in the presence of the strong Coulomb interaction, which significantly enhances the injection rate.

Highly efficient blue organic light-emitting diodes using various hole and electron confinement layers

In this Letter, blue phosphorescence organic light-emitting diodes （PHOLEDs） employ structures for electron and/or hole confinement; 1,3,5-tris（N-phenylbenzimiazole-2-yl）benzene is used as a hole confinement layer and tris-（phenylpyrazole）iridium [Ir（ppz）3] is utilized for an electron confinement layer （ECL）. The electrical and optical properties of the fabricated blue PHOLEDs with various carrier-confinement structures are analyzed. Structures with a large ehergy offset between the carrier confinement and emitting layers enhance the charge-carrier balance in the emitting region, resulting from the effective carrier confinement. The maximum external quantum efficiency of the blue PHOLEDs with the double-ECLs is 24.02% at 1500 cd/m^2 and its luminous efficiency is 43.76 cd/A, which is 70.47% improved compared to the device without a carrier-confinement layer.

Study on Electronic Conductivity of CaO-SiO2-Al2O3-FeOx Slag System

A study on electronic conductivity of CaO-SiO2-Al2O3-FeOxslag system with Wagner polarization technique was carried out.The experimental data show that electronic conductivity is consisted of free electron conductivity and electron hole conductivity and both are related to the content of Fe3+and Fe2+.Free electron conductivity is decreasing and electron hole conductivity is increasing while Fe3+changes to Fe2+.There is a maximum electronic conductivity at some ratio of ferric ions Fe3+to total ion content.Under the experimental conditions,the electronic conductivity is in the range of 10-4—10-2S/cm.

Electron acceleration by Langmuir turbulence in ionospheric heating

In this study,we investigate the generation of parametric decay instability,Langmuir turbulence formation,and electron acceleration in ionospheric heating via a two-fluid model using the Fokker-Planck equation and Vlasov-Poisson system simulations.The simulation results of both the magnetofluid model and the kinetic model demonstrate the dynamics of electron acceleration.Further,the results of the Vlasov-Poisson simulations suggest the formation of electron holes in phase space at the same spatial scale as the Langmuir wave,which are shown to be related to electron acceleration.In addition,electron acceleration is enhanced through the extension of the wavenumber spectrum caused by strong Langmuir turbulence,leading to more electron holes in phase space.

New Method for Diagnostics of Ion Implantation Induced Charge Carrier Traps in Micro- and Nanoelectronic Devices

An important problem of defect charging in electron-hole plasma in a semiconductor electronic device is investigated using the analogy of dust charging in dusty plasmas. This investigation yielded physical picture of the problem along with the mathematical model. Charging and discharging mechanism of charge carrier traps in a semiconductor elec-tronic device is also given. Potential applications of the study in semiconductor device technology are discussed. It would be interesting to find out how dust acoustic waves in electron-hole plasma in micro and nanoelectronic devices can be useful in finding out charge carrier trap properties of impurities or defects which serve as dust particles in elec-tron-hole (e-h) plasma. A new method based on an established technique “deep level transient spectroscopy” (DLTS) is described here suggesting the determination of properties of charge carrier traps in present and future semiconductor devices by measuring the frequency of dust acoustic waves (DAW). Relationship between frequency of DAW and properties of traps is described mathematically proposing the basis of a technique, called here, dust mode frequency deep level transient spectroscopy (DMF-DLTS).

The influence of trapping centres on the photoelectron decay in silver halide

Photoelectron is the foundation of latent image formation, the decay process of photoelectrons is influenced by all kinds of trapping centres in silver halide. By analysing the mechanism of latent image formation it is found that electron trap, hole trap, and one kind of recombination centre where free electron and trapped hole recombine are the main trapping centres in silver halide. Different trapping centres have different influences on the photoelectron behaviour. The effects of all kinds of typical trapping centres on the decay of photoelectrons are systematically investigated by solving the photoelectron decay kinetic equations. The results are in agreement with those obtained in the microwave absorption dielectric spectrum experiment.

Statistical properties of kinetic-scale magnetic holes in terrestrial space

Kinetic-scale magnetic holes(KSMHs)are structures characterized by a significant magnetic depression with a length scale on the order of the proton gyroradius.These structures have been investigated in recent studies in near-Earth space,and found to be closely related to energy conversion and particle acceleration,wave-particle interactions,magnetic reconnection,and turbulence at the kineticscale.However,there are still several major issues of the KSMHs that need further study—including(a)the source of these structures(locally generated in near-Earth space,or carried by the solar wind),(b)the environmental conditions leading to their generation,and(c)their spatio-temporal characteristics.In this study,KSMHs in near-Earth space are investigated statistically using data from the Magnetospheric Multiscale mission.Approximately 200,000 events were observed from September 2015 to March 2020.Occurrence rates of such structures in the solar wind,magnetosheath,and magnetotail were obtained.We find that KSMHs occur in the magnetosheath at rates far above their occurrence in the solar wind.This indicates that most of the structures are generated locally in the magnetosheath,rather than advected with the solar wind.Moreover,KSMHs occur in the downstream region of the quasi-parallel shock at rates significantly higher than in the downstream region of the quasi-perpendicular shock,indicating a relationship with the turbulent plasma environment.Close to the magnetopause,we find that the depths of KSMHs decrease as their temporal-scale increases.We also find that the spatial-scales of the KSMHs near the subsolar magnetosheath are smaller than those in the flanks.Furthermore,their global distribution shows a significant dawn-dusk asymmetry(duskside dominating)in the magnetotail.